US4356797A - System for controlling air-fuel ratio - Google Patents

System for controlling air-fuel ratio Download PDF

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Publication number
US4356797A
US4356797A US06/174,377 US17437780A US4356797A US 4356797 A US4356797 A US 4356797A US 17437780 A US17437780 A US 17437780A US 4356797 A US4356797 A US 4356797A
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United States
Prior art keywords
air
output
fuel ratio
circuit means
detecting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US06/174,377
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English (en)
Inventor
Fujio Matsui
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Subaru Corp
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Fuji Jukogyo KK
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Filing date
Publication date
Priority claimed from JP9885079A external-priority patent/JPS5634940A/ja
Priority claimed from JP9885279A external-priority patent/JPS5634942A/ja
Priority claimed from JP9885179A external-priority patent/JPS5634941A/ja
Application filed by Nissan Motor Co Ltd, Fuji Jukogyo KK filed Critical Nissan Motor Co Ltd
Application granted granted Critical
Publication of US4356797A publication Critical patent/US4356797A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1486—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor with correction for particular operating conditions
    • F02D41/1488—Inhibiting the regulation
    • F02D41/1491—Replacing of the control value by a mean value

Definitions

  • the present invention relates to a system for controlling the air-fuel ratio of the air-fuel mixture for an internal combustion engine emission control system with a three-way catalyst, and more particularly to a system for controlling the air-fuel ratio of a value approximately equal to the stoichiometric air-fuel ratio for the air-fuel mixture so as to effectively operate the three-way catalyst.
  • Such a system as in U.S. Pat. No. 4,132,199 is a feedback control system, in which an oxygen sensor is provided to sense the oxygen content of the exhaust gases to generate an electrical signal as an indication of the air-fuel ratio of the air-fuel mixture supplied to the engine.
  • the control system operates to compare the feedback signal from the oxygen sensor with a reference value corresponding to the stoichiometric value for producing the error signal and to control the air-fuel ratio of the mixture to be induced in the engine in accordance with the error signal.
  • Such a feedback control system inherently oscillates due to the detection delay of the oxygen sensor and the control delay in the system.
  • the oscillation of the system causes the variation of the controlled air-fuel ratio relative to the stoichiometric value.
  • Such a variation is increased during acceleration of the engine. Consequently, the emission control cannot accomplish a desired reduction of the harmful constituents of the exhaust gases.
  • the object of the present invention is to provide a system for controlling the air-fuel ratio which may decrease the variation of the air-fuel ratio relative to the stoichiometric value thereby bringing about the effective operation of the three-way catalyst.
  • a comparator for comparing the output signal of the detecting means with a reference value
  • an integration circuit for integrating the output of the comparator
  • a middle value detecting circuit for providing a plurality of middle values between two adjacent maximum and minimum values of the output of the integrating circuit
  • a driving circuit for generating an output in dependency upon the output signal of the middle value detecting circuit for driving the electromagnetic valve, whereby the air-fuel ratio is controlled to a value substantially equal to the stoichiometric air-fuel ratio.
  • FIG. 1 is a schematic view of a system for controlling the air-fuel ratio according to the present invention
  • FIG. 2 is a block diagram of an electric control circuit according to the present invention
  • FIG. 2a shows a middle value detecting circuit
  • FIG. 3 shows waveforms at various portions in the circuit of FIG. 2,
  • FIG. 4 shows wave forms for explaining the operation of a comparator in FIG. 2,
  • FIG. 5(A) shows an example of a waveform of the exhaust gas constituents
  • FIG. 5(B) shows a waveform of the output of an oxygen sensor in a conventional system
  • FIG. 5(C) shows a waveform of the output of an oxygen sensor in the system of the present invention.
  • a carburetor 1 communicates with an internal combustion engine 2.
  • the carburetor comprises a float chamber 3, a venturi 4, a nozzle 5 communicating with the float chamber 3 through a main fuel passage 6, and a slow port 10 communicating with the float chamber 3 through a slow fuel passage 11.
  • Air correcting passages 8 and 13 are provided in parallel to a main air bleed 7 and a slow air bleed 12, respectively.
  • On-off type electromagnetic valves 14 and 15 are provided for the air correcting passages 8 and 13.
  • An inlet port of each on-off type electromagnetic valve communicates with the atmosphere through an air cleaner 16.
  • An oxygen sensor 19 is provided on an exhaust pipe 17 at the upstream side of a three-way catalyst converter 18 for detecting the oxygen content of the exhaust gases.
  • a throttle sensor 20 used in another embodiment of the invention is provided to detect the degree of opening of a throttle valve 9. Output signals of sensors 19 and 20 are sent to an electronic control circuit 21 for actuating the on-off type electromagnetic valves 14 and 15 to control the air-fuel ratio of the mixture to a value approximately equal to the stoichiometric air-fuel ratio.
  • the output signal of the oxygen sensor 19 is fed to a comparator 23 through an amplifier 22.
  • the comparator 23 operates to compare the input signal with a reference voltage applied from a reference voltage circuit 24 to produce an output higher or lower than the reference voltage.
  • the output is sent to a middle value detecting circuit 26 through an integration circuit 25.
  • the output voltage of the sensor When the air-fuel mixture is rich, the output voltage of the sensor is at a higher level than the voltage corresponding to the stoichiometric value, and when the mixture is lean, the output voltage is at a lower level.
  • the output signal of the oxygen sensor is fed to the comparator 23 through the amplifier 22.
  • the comparator 23 compares the input signal with the level applied from the slice voltage applied from the reference voltage circuit 24 to produce pulses as shown in FIG. 3(b).
  • the reference voltage is set to a value corresponding to the stoichiometric air-fuel ratio.
  • the output pulses are integrated in the integration circuit 25 as shown in FIG. 3(c).
  • the middle value detecting circuit 26 determines the middle value C 0 between the maximum and minimum voltages of each linear section C 1 of each integrated triangular wave C 0 .
  • FIG. 3(d) shows the variation of the middle values.
  • FIG. 5(A) shows an example of the variation of the oxygen concentration of the exhaust gases.
  • FIG. 5(B) shows a corresponding variation of the output of the oxygen sensor in a conventional system.
  • the air-fuel ratio of the mixture is controlled in dependency on the detected signal of FIG. 5(A) and the controlled mixture is combusted in the cylinder of the engine and the combustion gases are detected by the oxygen sensor 19.
  • FIG. 5(B) shows the output of the sensor 19. From this figure, it will be seen that the deviation of the exhaust gas constituents of FIG.
  • the present invention resolves such a problem by using the middle value between the maximum and minimum values of the integrated wave as a reference signal. More particularly, as shown by the dotted line in FIG. 2, the output of the middle value detecting circuit 26 as shown in FIG. 3(d) the comparator is fed to circuit 31 for controlling the electromagnetic valves 14 and 15. By such a system, it is possible for the air-fuel ratio to approach the stoichiometric value. Farther, it will also be seen that since the middle value C 0 is decided when the output voltage of the integration circuit 25 reaches a maximum value (C 1 ), the middle value signal (C 0 ) is generated after the output of the circuit actually reaches the middle value. This occurs particularly in acceleration operation. Such a delay is shown by “Td” in FIG. 3(c). This delay will cause the control delay. In addition, the acceleration causes a large rise "R" (FIG. 5(A)) of the exhaust gas constituent waveform which induces the variation of the controlled air-fuel ratio.
  • the present invention further provides means which may prevent the control delay and the induced variation caused by the acceleration of the engine.
  • the throttle sensor 20 is provided.
  • the output signal of the throttle sensor 20 is fed to an acceleration and deceleration detecting circuit 27.
  • the detecting circuit 27 is adapted to produce an output voltage in dependency upon the acceleration and deceleration of the throttle value.
  • the outputs of the circuits 26 and 27 are summed by a summing circuit 28.
  • the output signal of the throttle sensor 20 is also sent to a pulse generator 29.
  • the pulse generator 29 generates a pulse train having a pulse-repetition frequency dependent upon the opening degree and the angular acceleration and deceleration of the throttle valve 9 and the acceleration and decelerating duration.
  • the outputs of the circuit 28 and 29 are fed to a summing circuit 30.
  • the output signal of the circuit 30 is compared in the comparator circuit 31 with triangular wave pulses from the triangular wave pulse generator 32 for producing square wave pulses
  • the output of the comparator circuit 31 is fed to the on-off type electromagnetic valves 14 and 15 via a driving circuit 33.
  • the throttle sensor 20 generates acceleration and deceleratio signals according to the operation of the engine as shown in FIG. 3(e).
  • the signals are differentiated in the acceleration and deceleration detecting circuit 27 as shown in FIG. 3(f).
  • the output (f) of the circuit 27 is added to the output (d) of the circuit 26 by the summing circuit 28.
  • the differentiated signal of FIG. 3(f) is generated before the middle value signal from the circuit 26.
  • the pulse generator 29 generates a pulse train (g), the pulse-repetition frequency of which varies according to the degree of opening and the angular acceleration and deceleration of the throttle valve 9 and the acceleration and deceleration duration.
  • FIG. 3(g) shows the repetition frequency according to the acceleration and deceleration of FIG. 3(e).
  • the pulse train of FIG. 3(g) is added to the corrected middle value output signal of the circuit 28 by the summing circuit 30.
  • the corrected middle value output is converted into a pulse train as shown in FIG. 3(h) and the pulse-repetition frequency during a period according to the acceleration and deceleration of FIG. 3(e) increases.
  • the (h) output of the summing circuit 30 is compared with the triangular wave pulses from the pulse generator 32 in the comparator circuit 31. As shown in FIG. 3(i) and FIG. 4, the output signal (h) is compared with and slices the triangular wave pulses (i), so that output pulses (j) are produced. The output pulses are fed to the on-off type electromagnetic valves 14 and 15 through the driving circuit 33 to actuate the valves.
  • FIG. 5(C) shows the variation of the air-fuel ratio in the control system of the present invention, in which the air-fuel ratio is controlled to a small range relative to the stoichiometric air-fuel ratio.
  • the feedback signal from the oxygen sensor is compared with the desired reference value to produce the error signal, and the error signal is integrated and, middle values between maximum and minimum values of the integrated wave are detected, and the middle values are converted into a driving signal for driving the electromagnetic valve.
  • the variation of the controlled air-fuel ratio can be decreased.
  • control delay caused by acceleration can be corrected by compensation with the differentiated signal, and the response may be quickened by increasing the pulse-repetition frequency of the driving pulse.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Control Of The Air-Fuel Ratio Of Carburetors (AREA)
US06/174,377 1979-08-02 1980-08-01 System for controlling air-fuel ratio Expired - Lifetime US4356797A (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP54-98852 1979-08-02
JP9885079A JPS5634940A (en) 1979-08-02 1979-08-02 Air-fuel ratio control apparatus
JP54-98850 1979-08-02
JP54-98851 1979-08-02
JP9885279A JPS5634942A (en) 1979-08-02 1979-08-02 Air-fuel ratio control system
JP9885179A JPS5634941A (en) 1979-08-02 1979-08-02 Air-fuel ratio control system

Publications (1)

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US4356797A true US4356797A (en) 1982-11-02

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US06/174,377 Expired - Lifetime US4356797A (en) 1979-08-02 1980-08-01 System for controlling air-fuel ratio

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US (1) US4356797A (fr)
DE (1) DE3029325C2 (fr)
FR (1) FR2463282B1 (fr)
GB (1) GB2056723B (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4402292A (en) * 1980-03-07 1983-09-06 Fuji Jukogyo Kabushiki Kaisha Air-fuel ratio control system
US4407244A (en) * 1981-06-27 1983-10-04 Aisin Seiki Kabushiki Kaisha Apparatus for controlling the proportion of air and fuel in the air-fuel mixture of the internal combustion engine
US4452209A (en) * 1981-01-16 1984-06-05 Fuji Jukogyo Kabushiki Kaisha Air-fuel ratio control system for an internal combustion engine
US4705011A (en) * 1985-10-09 1987-11-10 Honda Giken Kogyo Kabushiki Kaisha Air intake side secondary air supply system for an internal combustion engine with an improved operation for a large amount of the secondary air
US4715349A (en) * 1985-10-05 1987-12-29 Honda Giken Kogyo Kabushiki Kaisha Air intake side secondary air supply system for an internal combustion engine with an improved operation under a small intake air amount
US4715352A (en) * 1985-09-30 1987-12-29 Honda Giken Kogyo Kabushiki Kaisha Air intake side secondary air supply system for an internal combustion engine with a duty ratio control operation
US5416710A (en) * 1990-05-08 1995-05-16 Honda Giken Kogyo K.K. Method of detecting deterioration of a three-way catalyst of an internal combustion engine
US20080306647A1 (en) * 2007-06-11 2008-12-11 Jae Wook Jeon In-vehicle network system and control method thereof

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5660845A (en) * 1979-10-20 1981-05-26 Mazda Motor Corp Air-fuel ratio control device for engine
US4432324A (en) * 1981-04-08 1984-02-21 Toyota Jidosha Kogyo Kabushiki Kaisha Air-fuel ratio control device of an internal combustion engine
DE3149096A1 (de) * 1981-12-11 1983-06-16 Robert Bosch Gmbh, 7000 Stuttgart Verfahren zur lambda-regelung bei einer brennkraftmaschine sowie entsprechendes regelsystem
EP0112673A1 (fr) * 1982-12-13 1984-07-04 Solex (U.K.) Limited Appareil électronique pour commander l'alimentation en carburant d'un moteur à combustion interne
US4520784A (en) * 1983-08-05 1985-06-04 Toyota Jidosha Kabushiki Kaisha Method of and apparatus for controlling fuel injection

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4023357A (en) * 1974-12-24 1977-05-17 Nissan Motor Co., Ltd. System to control the ratio of air to fuel of the mixture delivered to an internal combustion engine
US4029061A (en) * 1974-10-21 1977-06-14 Nissan Motor Co., Ltd. Apparatus for controlling the air-fuel mixture ratio of internal combustion engine
US4171690A (en) * 1976-03-08 1979-10-23 Nissan Motor Company, Limited Emission control system for internal combustion engines utilizing balance differential amplifier stage
US4187812A (en) * 1976-07-13 1980-02-12 Nissan Motor Company, Limited Closed loop fuel control with sample-hold operative in response to sensed engine operating parameters
US4237839A (en) * 1978-06-22 1980-12-09 Nippon Soken, Inc. Air-fuel ratio detecting system

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1523512A (en) * 1975-02-06 1978-09-06 Nissan Motor Closed loop air-fuel ratio control system for use with internal combustion engine
JPS51124738A (en) * 1975-04-23 1976-10-30 Nissan Motor Co Ltd Air fuel ratio control apparatus
JPS5840010B2 (ja) * 1975-12-27 1983-09-02 日産自動車株式会社 クウネンピセイギヨソウチ
JPS5297025A (en) * 1976-02-09 1977-08-15 Nissan Motor Co Ltd Air fuel ration controller
JPS538431A (en) * 1976-07-12 1978-01-25 Hitachi Ltd Air-to-fuel ratio control means for engine
JPS5950863B2 (ja) * 1976-10-08 1984-12-11 日産自動車株式会社 空燃比の制御方法およびその装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4029061A (en) * 1974-10-21 1977-06-14 Nissan Motor Co., Ltd. Apparatus for controlling the air-fuel mixture ratio of internal combustion engine
US4023357A (en) * 1974-12-24 1977-05-17 Nissan Motor Co., Ltd. System to control the ratio of air to fuel of the mixture delivered to an internal combustion engine
US4171690A (en) * 1976-03-08 1979-10-23 Nissan Motor Company, Limited Emission control system for internal combustion engines utilizing balance differential amplifier stage
US4187812A (en) * 1976-07-13 1980-02-12 Nissan Motor Company, Limited Closed loop fuel control with sample-hold operative in response to sensed engine operating parameters
US4237839A (en) * 1978-06-22 1980-12-09 Nippon Soken, Inc. Air-fuel ratio detecting system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4402292A (en) * 1980-03-07 1983-09-06 Fuji Jukogyo Kabushiki Kaisha Air-fuel ratio control system
US4452209A (en) * 1981-01-16 1984-06-05 Fuji Jukogyo Kabushiki Kaisha Air-fuel ratio control system for an internal combustion engine
US4407244A (en) * 1981-06-27 1983-10-04 Aisin Seiki Kabushiki Kaisha Apparatus for controlling the proportion of air and fuel in the air-fuel mixture of the internal combustion engine
US4715352A (en) * 1985-09-30 1987-12-29 Honda Giken Kogyo Kabushiki Kaisha Air intake side secondary air supply system for an internal combustion engine with a duty ratio control operation
US4715349A (en) * 1985-10-05 1987-12-29 Honda Giken Kogyo Kabushiki Kaisha Air intake side secondary air supply system for an internal combustion engine with an improved operation under a small intake air amount
US4705011A (en) * 1985-10-09 1987-11-10 Honda Giken Kogyo Kabushiki Kaisha Air intake side secondary air supply system for an internal combustion engine with an improved operation for a large amount of the secondary air
US5416710A (en) * 1990-05-08 1995-05-16 Honda Giken Kogyo K.K. Method of detecting deterioration of a three-way catalyst of an internal combustion engine
US20080306647A1 (en) * 2007-06-11 2008-12-11 Jae Wook Jeon In-vehicle network system and control method thereof

Also Published As

Publication number Publication date
FR2463282B1 (fr) 1986-05-02
DE3029325A1 (de) 1981-02-26
GB2056723A (en) 1981-03-18
DE3029325C2 (de) 1986-09-18
GB2056723B (en) 1983-07-06
FR2463282A1 (fr) 1981-02-20

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